Saturday, August 30, 2008

HTML stands for Hyper Text Markup Language. It is a formatting language used to develop web pages. Hypertext means that HTML makes certain words in the document as links to other parts of the same document or other document. When the user clicks on a link, the browser starts displaying the document attached to the link.

HTML is not a programming language. It is used to define text, graphics, audio and video in web pages. It uses tags or markups to specify how the concept of web pages will be displayed. HTML code can be written in any text editor like notepad.

HTML was developed a few years ago as a subset of SGML. SGML stands for Structured Generalized Mark-up Language. It also describes formatting and hypertext links and different component of a document. It is basically an application oriented document format. SGMl is not ideal for transmission across the Internet to different type of computers and browser applications.

HTML is simpler then SGML. It was designed for the use over the Internet in the form of Web pages. HTML is more suited for this purpose. It is used to design and create pages for different types of users of the Web.

In every HTML document, and tags indicate the begining and end of the document respectively. These tags inform the browser that the document is an HTML file. All other HTML tags must be written within these tags. The v document can be divided into two sections:

1-Header Section
2-Body Section

Header Section and tags identify the heading or title of document. The text between these tags appears as title in the browser's window. Its length should not be more than 60 characters.

Body Section

The body of an HTML document contains the text that is displayed on a web page. The body section is enclosed within and tags. It gives a description of the document layout and structure.

Database is an organized collection of related data that is stored in an efficient and compact manner. The word organization means that data is stored in such a way that the user can use this data easily. The word related means that a database is normally created to store the data about a particular topic. The word efficient means that the user can search the required data quickly. The word compact means that the stored data occupies as little space as possible in computer.

Some examples of database are :

Phone Directory

It is a simple example of a database. A phone directory stores the phone numbers of different persons. Any phone number from the phone directory can be searched easily because all phone numbers are stored in an organized way.

Library

A library contains thousands of books. A database system can be used to store the records of books. The database can be used to search the required books easily.

Accounts

A database is used to control the accounts system of an organization. The accounts database keeps the record of all financial transactions of the organization.

College Record

A college has many students in different classes. A database is used to store the records of the students, fee transactions, examination information and attendance of the students.These are few simple examples of database. The list is almost endless.

A database management system (DBMS) is a collection of computer programs that are used to create, maintain and access database in a convenient and efficient manner.

Characteristics

The most important characteristics of database management system are :

1-Efficiency2-Compactness

Efficiency

A database management system stores, retrieves and manipulates data in a database with efficiency. It takes far less time to manipulate data as compared to file system. It uses the processing power of the computer to increase its efficiency.

Compactness

Compactness refers to the way of storing data in a database. A database management system stores data in less space than file system. The storage capacity of the computer is used properly.

Friday, August 29, 2008

Internet has provided easy way to share information and data but there are so many services which is available on the Internet. Following are some important services of the Internet.

Advertisement Internet is used for the advertisement of different products. Manufacturers provide information about their products. In this way, they give more exposure to their products.

Online Shopping

Now it is possible for a user to buy a product using Internet. there are many online shopping store where we can see products and their prices. We can simply order these products using a credit card.

Flight Information

Airlines provide the schedule of flights on their websites. We can easily get latest information on flights arrivals and departures.

Television Station

Almost all T.V channels have their website which is used to provide information about the programs, the latest news and special events. Some televisions show their events live on their website.

Encyclopedia Publisher

Online encyclopedias are available. You can find detailed information on any topic in the world. Wikipedia is an example of it.

Search Engines

search engine is a website that provides you the facility to find the required websites on a particular topic. You can find thousands of websites about any topic. The famous search engines are Google, AltaVista, Yahoo and Lycos etc.

Medical

Many websites in the world provide detailed information on diseases. You can also consult a panel of on-line Doctors to get the advise about any medical problem.

The work on Internet was started in 1960's during the cold war of Russia and America. A network of 4 computers was developed at start.

ARPANETDuring the cold war, Russia launched Sputnik satellite and America developed a network. Its name was ARPANET. It was developed for Advance Research Project Agency (ARPA).

ProtocolProtocol is a collection of rules. In 1970's NCP (Network Control Protocol) was developed. It was the first standard protocol for data transfer.

DARPA

It stands for Defense Advanced Research Projects Agency. It was a new name of ARPA . Now 37 computers were connected together. It started work to share data not only to a single network but also among other different networks. Stanford Research Institute took part in this research.

TCP/IPA team of Stanford Research Institute developed a protocol called TCP/IP . It stands for Transmission Control Protocol/Internet Protocol. It was designed to share data among different networks.

BITNET AND CSNETBITNET stands for Because It's Time Network and Csnet stands for Computer Science Network. These were established for non-military persons. These networks were used for academic and research purpose. In these networks, IBM computers and university computers were connected together.

World Wide NetworkSoon the idea of Internet same out. Different universities and Research institutes started work on a global network. In 1986, NSFNet was developed. It connected academic researches of different countries.

Internet

Internet is now the largest network in the world. millions of computers are connected together through different medium. People can share information and data. Any computer with a modem and telephone line can become part of the Internet